High speed roll for machinery

ABSTRACT

A press roll for paper making machinery has a mandrel, characteristically composed of a two phase system with an external phase containing a synthetic polymeric matrix and an internal phase containing aligned continuous carbon fibers. The construction of this press roll permits unusually high speed operation.

United States Patent Hess et al.

[54] HIGH SPEED ROLL FOR MACHINERY [72] Inventors: Ralph A. Hess, Medtield, Mass;

James P. McNamee, Pawtucket, R.l.

[73] Assignce: SW Industries, Inc., Newton, Mass.

[22] Filed: May 6, 1971 [2]] Appl. No.: 140,722

Related US. Application Data [63] Continuation-in-part of Ser. No. 857,186, Sept.

11, 1969, Pat. No. 3,593,398.

[52] US. Cl ..29/132 [51] Int. Cl. ..B21b 31/08 [58] Field of Search ..29/l32, 130, 129.5

[56] References Cited UNITED STATES PATENTS 2/1946 Bacon .;.....29/l32 X 1 Oct. 17, 1972 2,597,858 5/1952 Freedlander ..29/l32 X 2,997,406 8/1961 Freeman et a1. ..29/1 30 X 3,336,862 8/1967 Brundige et a1 ..29/132 X 3,395,636 8/1968 Hess ..29/132 X 3,593,398 7/1971 Hess et a1. ..29/132 Primary Examiner-Alfred R. Guest Attorney-Morse, Altman & Oates [57] ABSTRACT A press roll for paper making machinery has a mandrel, characteristically composed of a two phase system with an external phase containing a synthetic polymeric matrix and an internal phase containing aligned continuous carbon fibers. The construction of this press roll permits unusually high speed operation.

5 Claims, 5 Drawing Figures REFERENCE TO OTHER APPLICATIONS This application is a continuation in part of our application, Ser. No. 857,186, filed Sept. 11, 1969, now issued as Pat. No. 3,593,398 on July 20,1971.

BACKGROUND AND SUMMARY The present invention relates to rolls for machinery and, more particularly, to rolls of the type used, for example, in paper making machinery. Typically, such a roll has a metal core that is characterized by resonant bending, torsional and whirl vibration during operation. At their resonant frequencies, these vibrations are attended by large amplitude strains which can be detrimental to the integrity of the roll. In order to avoid the occurrence of such resonant frequencies, it has been necessary to limit the rotational speed of press rolls in paper making machinery. In consequence, undue limitations have been placed on production capacity of such paper making machinery.

The primary object of the present invention is to provide an extremely 'rigid press roll having a mandrel characterized by extremely high resonant vibrational 'frequenciesby virtue of a two phase composition comprising an external phase containing a synthetic polymeric matrix and an internal phase containing generally parallel, continuous carbon fibers. The high tensile strength of the carbon fibers and their bonding compatibility with the polymeric matrix cooperate to provide (1) extremely high rigidity by which resonant frequencies within the mandrel are increased beyond the frequencies that naturally occur during high speed operation, and (2) the surface of the roll is characterized by corrosion resistance for direct contact with an advancing wet paper web or good adhesion to an elastomeric veneer of selected surface properties. It is found that specifically such rolls are stiffer and lighter than corresponding steel rolls, in consequence of which, they can be operated at unusually high speeds without resonant vibration.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the devices, products and processes, together with their components, parts, steps and interrelationships, which are exemplified by the following disclosure, the scope of which will be indicated in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the nature and objects of the present invention, reference is made to the following detailed description, taken in connection with the accompanying drawings, wherein:

FIG. I illustrates in exaggerated cross section, several different rolls embodying the present invention;

FIG. 2(a) (b) (c) illustrate materials undergoing processes for producing rolls in accordance with the present invention; and

FIG. 3 is a schematic illustration of parts of a paper making machine, comprising rolls construed in accordance with the present invention.

DETAILED DESCRIPTION Generally, each of the rolls illustrated herein as embodying the present invention is a cylindrical mandrel shell of high modulus of elasticity, characterized by a composition containing an external phase in the form of a synthetic polymer and an internal phase in the form of continuous carbon fibers, each composed of contiguous carbon filaments. In one form, the polymeric matrix is composed of an epoxy or an imide. In one form, the carbon filaments are characterixed by the presence of a linear carbon chain and a minimum of carbon substituents. Such carbon filaments, for example, are produced by synthetic a xynthetic polymer such as acrylonitrile. Preferably, the two phase composition contains, by total weight, from 30 to percent resin matrix and from 70 to 30 percent carbon filament. It has been found that, with press rolls ranging from 12 to 60 inches in diameter, 36 to 480 inches in length and A to 3 inches in shell thickness, peripheral speeds of 1,000 to 5,000 feet per minute are possible without reaching resonant frequencies.

Details of various configurations of rolls, constructed in accordance with the present invention, are shown in FIG. 1. FIG. I( a), the roll is shown ashaving an annular cross sectional configuration, characterized by an outer annulus l0 and an inner hollow l2. Annulus 10 is composed of a polymeric matrix and carbon fibers in accordance with the present invention. In FIG. 1(b), the roll is shown as having an annular mandrel 14 of the type shown at 10 in FIG; 1(a) and an outer elastomeric veneer l6, composed for example, of a natural or synthetic rubber composition. In FIG. 1(c), the roll is shown as having annular configuration l8-of the same composition as that at 10in FIG. 11(a) and an inner annular mandrel 20 composed of paper, for example a paper impregnated with a sizing agent, a plastic, for example a heat resistant polymer such as a phenolic, or a metal, for example aluminum. In each casethe stiffness of the roll is controlled by the resin and car filament shell.

One method of fabricating annular mandrels of the type shown in FIGS. 1 (a) and (c) is shown in FIG. 2(a) as involving an extrusion die 28 having an extrusion slit 30, through which a composition of unpolymerized matrix and carbon fibers is ejected at 32. Another method of fabricating a roll of the foregoing type is to coil, around a form 34, or to apply along the axis of form 34 a continuous strip 36, composed of unpolymerized matrix 38 and carbon filaments 35 of the type shown in FIG. 2. Following polymerization under appropriate heat and pressure, the resulting'coat is self supporting and the form 34 either is removed as in FIG. 1 (a) or is retained as in FIGS. 1(b) and 1(c).

By way of example, a typical application of the rolls described above is illustrated in a paper making machine, shown in part in FIG. 3. In a typical paper making process, a dilute aqueous slurry of cellulose fiber, first is cast onto an endless wire screen through which water is drained, next is advanced onto an endless felt, with which it passes between a series of so called press rolls that squeeze and withdraw water therefrom, next is advanced by itself between series of press rolls and then is advanced over heat drying cylinders. Difficulties have been encountered as a result of the tendency of these rolls to vibrate as they rotate in contact with the web. Three types of vibrations occur, namely bending vibrations, torsional vibrations and whirl vibrations, and all have resonant frequencies. In accordance with the present invention, the stiffness of the rolls is so high that these resonant frequencies do not occur at the high operating speeds selected. More particularly, in the illustrated paper making process, the initial web sheet 40 is formed by casting a dilute, aqueous slurry 39 of cellulose fibers onto an endless wire screen 41. In accordance with the present invention, endless sire screen 41 is supported on a series of table rolls 42 and controlled by guide rolls 57. From table rolls 42, web 40 is advanced into contact with a so-called fly roll 48 and then onto a series of endless felts 52. Then sheet 40 advances together with endless felts 52 into the nips between a series of press rolls 54, 56, which are in association with felt control rolls 58. In accordance with the present invention, press rolls 54, 56 are composed of the resin matrix and carbon fiber dispersoid composite of the present invention.

The following non-limiting example further illustrates the process for fabricating the product of the present invention.

' EXAMPLE A roll of the type shown in FIG. 2(a) is fabricated by coiling an uncured polymer and carbon filament composite strip 36 about an aluminum cylinder 34. Aluminum cylinder 34 is 15 inches in outer diameter and 200 inches long, with wall thickness of one-half inch. The composite strip, by total weight, contains 50 percent polymer and 50 percent carbon fiber. The polymer is a polyester, specifically a diglicidyl ether of bisphenol, sold by Celanese under the trade designation EPl-REZ 508. The carbon filaments are composed of carburized polyacrylonitrile and have a tensile modulus greater than X l psi, an ultimate tensile strength of 325-350 X 10 psi, a density of 1.95 to 2.10 gm per cc and a twist of no greater than one turn per inch. The coat formed by coiling the carbon strip about the tube is approximately one-half inch thick. The entire tube is cured at 93 C. for 2 hours and then at 200 C. for 2 hours, at a constant pressure of 150 psi throughout the cure. The resulting resin and carbon fiber matrix has a hardness ranging from to 95 Shore D and an unusually high modulus of elasticity to weight ratio.

Since certain changes may be made in a foregoing disclosure, without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings, be interpreted in an illustrative and not in a limiting sense.

What is claimed is:

l. A press roll in the form of a cylindrical shell ranging in diameter from 12 to 60 inches, ranging in length from 36 to 480 inches and ranging in shell wall thickness from A. to 3 inches, said cylindrical shell being composed of two phase composition having a synthetic polymeric matrix and continuous generally parallel carbon fibers, said composition by total weight containing from 30 to 70 percent polymeric matrix and from 70 to 30 percent carbon fibers.

2. The roll of claim 1 wherein said polymeric matrix is composed of a member of the class consisting of epoxies and pol yimides.

3. The rol 0 claim 1 wherein said carbon fibers are characterized by linear carbon chains with minimum substituents.

4. The press roll of claim 1 wherein said two phase composition has a hardness ranging from 70 to 95 Shore D.

5. The press roll of claim 1 wherein said synthetic polymeric external phase is composed of a diglycidyl ether of bisphenol and said carbon filament internal phase is composed of spaced elongated carbon filaments characterized by a minimum of substituents. 

2. The roll of claim 1 wherein said polymeric matrix is composed of a member of the class consisting of epoxies and polyimides.
 3. The roll of claim 1 wherein said carbon fibers are characterized by linear carbon chains with minimum substituents.
 4. The press roll of claim 1 wherein said two phase composition has a hardness ranging from 70 to 95 Shore D.
 5. The press roll of claim 1 wherein said synthetic polymeric external phase is composed of a diglycidyl ether of bisphenol and said carbon filament internal phase is composed of spaced elongated carbon filaments characterized by a minimum of substituents. 